1. Field of the Invention
The present invention generally relates to a plasma display panel (PDP), and more particularly, to a plasma display panel that can adjust color temperature by utilizing area of an electrode pair.
2. Description of Related Art
Plasma display panels (PDPs) have been gradually applied to large sized displaying apparatuses. The light source comes from plasma, which is initiated by electrodes, to produce ultraviolet rays. When the ultraviolet rays shine incident on different fluorescent materials, the fluorescent materials will emit visible lights having different wavelengths.
Referring to FIG. 1, it is a schematic diagram of a plasma display panel 10 according to the prior art. The prior art plasma display panel 10 comprises a housing (not shown), a rear plate 12, and a front plate 14 disposed parallel with and spaced apart from the rear plate 12. A plurality of electrode pairs 16 are disposed on a bottom surface of the front plate 14.
Each electrode pair 16 comprises a common electrode 17 and a scanning electrode 18. A dielectric layer 20 is disposed on the bottom surface of the front plate 14 to cover the electrode pairs 16 so as to protect the electrode pairs 16. A protective layer 22 composed of magnesium oxide (MgO) is disposed underneath the dielectric layer 20 to protect the dielectric layer 20 from being degraded due to sputtering. A plurality of barrier ribs 24 are disposed on the rear plate 12. A plurality of data electrodes 26 are disposed between two adjacent barrier ribs 24. Three different fluorescent materials, including blue, red, and green fluorescent materials 30B, 30R, 30G are filled between two adjacent barrier ribs 24. The space between two adjacent barrier ribs 24 is filled with a discharge gas. The top ends of the plurality of barrier ribs 24 are fixed to a bottom surface of the protective layer 22 to isolate the plasma at either side of the barrier ribs 24 so as to avoid the cross-talk problem.
Each of the common electrodes 17 and the scanning electrodes 18 respectively comprises a sustaining electrode 36 and a bus electrode 38. The sustaining electrode 36, usually made of indium tin oxide (ITO), is a wide transparent conductor and is used for initiating and sustaining the discharge. The bus electrode 38, usually made of a Chrome/Copper/Chrome (Cr/Cu/Cr) metal alloy, is a narrow and non-transparent metal line. The bus electrode 38, being in parallel with the sustaining electrode 36, is disposed on a surface of the sustaining electrode 36 to assist the sustaining electrode 36 with initiating discharge and reducing the resistance of the common electrode 17 and the scanning electrode 18. As shown in FIG. 1, a plurality of display cells, partitioned by two adjacent barrier ribs 24, are defined at an intersection of each data electrode 26 and each electrode pair 16. Each display cell comprises a first display cell 32B for displaying blue light, a second display cell 32R for displaying red light, and a third display cell 32G for displaying green light.
When a voltage is applied between the electrode pair 16 and the data electrode 26 in each display cells 32B, 32R, 32G, an electric field is generated between the electrode pair 16 and the data electrode 26 to initiate discharge so as to produce ultraviolet rays. When the ultraviolet rays shine incident on different fluorescent materials 30B, 30R, 30G, the fluorescent materials will emit lights. The factors affecting the luminous efficiency of each of the display cells 32B, 32R, 32G include the kind of the discharging gas, the material of the electrode, and the luminous efficiency of the fluorescent material.
In order to improve the luminescent quality of the plasma display panel 10, the color temperature of the plasma display panel 10 should be increased. However, the luminous efficiency of the green fluorescent material 30G is the highest one, the luminous efficiency of the blue fluorescent material 30B is the lowest one, and the luminous efficiency of the red fluorescent material 30R is in between. Under the same situation, the luminosity of the display cells 32B, 32R, 32G is different from each other so that an inhomogeneous problem is incurred. Therefore, the color temperature of the plasma display panel 10 is not able to be increased.
Referring to FIG. 2, it is a schematic diagram of another plasma display panel 40 according to the prior art. The major difference between the plasma display panel 40 and the plasma display panel 10 is the space between the adjacent barrier ribs 44. The barrier ribs 24 of the plasma display panel 10 are arranged with an equal space, while the barrier ribs 44 of the plasma display panel 40 are not arranged with an equal space. As shown in FIG. 2, the space covered by the blue fluorescent material 30B is the widest one, the space covered by the red fluorescent material 30R is the narrowest one, and the space covered by the green fluorescent material 30G is in between. Since the wider space is covered by more fluorescent materials, the luminosity of the display cells 32B, 32R, 32G in the plasma display panel 40 becomes homogeneous by adjusting the luminous efficiency of each of the fluorescent material 30B, 30R, and 30G so as to increase the color temperature.
Due to the unequal space between the barrier ribs 44 in the plasma display panel 40, some of the spaces between the adjacent barrier ribs 44 need to be made smaller in comparison with the space between the adjacent barrier ribs 24 in the plasma display panel 10, which has a same resolution as the plasma display panel 40. That means the manufacturing accuracy needs to be improved to fabricate the barrier ribs 44 with smaller space. Generally speaking, the space covered by the blue fluorescent material 30B needs to be 20% larger than the space covered by the green fluorescent material 30G and the space covered by the red fluorescent material 30R to obviously increase the color temperature. Since the resolution of the plasma display panel is continuously increased, this method provides difficulty in manufacturing. Furthermore, because the discharge space for the second display cell 32R in the plasma display panel 40 is shrunk greatly to reduce the luminosity of the red light emitted from the second display cell, the luminous efficiency of the plasma display panel 40 is reduced. In addition, due to the unequal space between the barrier ribs 44 in the plasma display panel 40, the discharge space for the first display cell 32B, the second display cell 32R, and the third display cell 32G is thus different from each other, resulting in an unmatched operational voltage margin problem.